CVE-2026-43864

Mail client crash via NULL key dereference

Published May 4, 2026 · Updated May 4, 2026

NULL pointer dereference in Mutt before 2.3.2 allows attackers to crash the mail client while signature status is displayed. The show_sig_summary function dereferences key->subkeys for an expired-key signature even when show_one_sig_status supplies a NULL key after GPG_ERR_NO_PUBKEY. Exploitation requires user interaction and a high-complexity local trigger; the documented consequence is interruption of the Mutt process only.

CVSS severity2.5
Low
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Mutt before 2.3.2 allows attackers to crash the mail client while signature status is displayed. The show_sig_summary function dereferences key->subkeys for an expired-key signature even when show_one_sig_status supplies a NULL key after GPG_ERR_NO_PUBKEY. Exploitation requires user interaction and a high-complexity local trigger; the documented consequence is interruption of the Mutt process only.

The record

CVE
CVE-2026-43864
Published
May 4, 2026
Updated
May 4, 2026
Vendor
Mutt
Product
Mutt
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2026CVE publishedPublication date reported by the CVE source.
  2. May 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2.3.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Mutt · Muttversion=0 <2.3.2

Published CVSS scores

2.5MITRECVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
2.0SUSECVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
2.5SUSECVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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